WTS Wednesday Presents The Science Behind Invisible Ink!


Hello ‘Tangenters!

PB_scientist_vial_500x500If you follow PB’s Facebook feed (if you’re not… you should start!), you’ll know that he’s planning a lot of really cool tubes (and costumes!) for his new game. And, he’s using a lot of science  to do it!

So, this week I have a fun, secret-agent type of activity just for you! But more importantly, I’ve got the SCIENCE behind it!

We’re going to make invisible ink from lemon juice! (Many of you parents out there probably remember doing this as a kid!)

Is the Mission: Impossible theme playing in your head, too?


  • Paper
  • Cotton swab/paintbrush/toothpick – Whatever you use just needs to be something that will transfer your invisible ink to the paper.
  • Lemon – This is the super, top-secret ingredient!
  • Heat gun/incandescent light bulb/hair dryer – Basically, you will need something that will heat the ink up enough to show up.

iStock_Lemons_419x286 Photo By Stefano Tiraboschi

How To!

  • Juice the lemon.
  • Dip the cotton swab or paintbrush into the lemon juice and you (or your child… if you want him or her to have fun, too, I guess) can either write or draw something on the piece of paper (don’t use too much lemon juice or it won’t be “invisible”).
  • Wait for your “ink” to dry.
  • Apply the heat! Either hold the paper close to the heat source or hold the heat source close to the paper. Based upon your child’s abilities he or she might be able to help with this part. NOTE: Be careful and don’t catch the paper on fire! It is scary and Not Fun™.  Don’t ask me how I know…
  • Watch the “ink” appear!! This should happen pretty quickly!

Now you can write secret notes to your heart’s content!

The Science!

iStock_KidsScienceExperiment_425x282 Photo by Morgan Lane Studios

You know how that avocado or sliced apple turns brown if you’ve left out for too long? Usually it still tastes fine, but it looks really unappetizing…

That is a process called oxidation. It occurs when certain compounds in these fruits are exposed to the air.

In order for the compounds in the lemon juice to oxidize, you must apply heat. This property is what makes it so great for invisible ink!

So, when your lemon juice turns brown… that’s oxidation! And that’s chemistry!

Here’s a link all about it!

Thanks to PB for inspiring this post. Follow him on Facebook if you want to learn more about his new game! And, make sure to play Polar Bowler 1st Frame (on iOS and Android) if you want your PB and J fix!
Related Posts:

Tags: , , , , , , , ,

No comments yet.

Leave a Reply